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Structural and magnetic studies of strongly correlated electronic systems

Understanding of strongly correlated systems is of great importance in our understanding of fundamental solid-state science, and in the design and improvement of many technologically useful magnetic systems. In this thesis studies of two such systems are presented. The first system is the jarosite mineral family AM<sub>3</sub>(SO<sub>4</sub>)<sub>2</sub>(OH)<sub>6</sub> (where A = H<sub>3</sub>O, K; M = Fe, Cr) which is an experimental manifestation of a kagome lattice antiferromagnet. Such a lattice displays unusual magnetic behaviour which may be of direct relevance to high temperature superconducting materials. A variety of neutron experiments have been performed to investigate the nature of the spin dynamics in the case of the hydronium iron salt, which is unique to the iron series in not exhibiting long range magnetic order. Single crystal studies have been used to probe the nature of the ground state of the potassium salt, and the first unambiguous determination of the magnetic structure is presented. Neutron diffraction studies and muon measurements have been performed on the hydronium chromium salt, the behaviour of which appears to contrast with that of the iron analogue. The second system of study is the series of compounds La<sub>l-x</sub>M<sub>x</sub>MnO<sub>3</sub> (where M = Ca,Pb) which are of interest due to their potential application in read-write head devices. A combination of both dc susceptibility measurements and neutron diffraction studies have been used to investigate the magnetic behaviour of both these systems in key areas of the temperature-composition phase diagrams. The electronic fluctuations in the calcium system have been studied using muon spin relaxation techniques.
Date January 2000
CreatorsOakley, Gareth S.
PublisherUniversity of Edinburgh
Source SetsEthos UK
Detected LanguageEnglish
TypeElectronic Thesis or Dissertation

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